I bought a new pair of HED Bastogne wheels recently, and at the urging of Dr. Wilkes had them converted to use with tubeless tires. I'm running Hutchinson Intrepid tires on them. Even on my already silky-smooth titanium bike, the tubeless ride, in combination with the wide rims of the HEDs, noticeably improves ride quality, while eliminating the possibility of pinch flats. If I ever get a big enough hole in the tires to cause them to flat, I can just slap in an ordinary tube and keep running them.
I haven't yet decided to convert my HED Jet C2 60s to tubeless. Doing so would require the continual use of a valve extender, which is a bit of a complicating factor.
It costs about $30 to convert the wheels to tubeless, and the tubeless tires are a bit more expensive than regular tires (mainly because only two companies currently make tubeless tires - Hutchinson and Specialized). I suspect that more tire companies will go tubeless in the new couple years, and the increased competition should cause prices to fall.